No they’re not different posters- in fact, if you’ll notice the corner of the Mazinger poster is just visible. It’s just we’ve never seen the room from this angle, and thus never seen the hockey poster.

Oh my God! That’s a speed racer blanket! There is no way a kid that age has ever seen Speed Racer… unless of course they showed it to him. But then again, how did he get his hands on such retro merchandise?